The area under investigation is the regulation of aldosterone secretion by angiotensin II as well as potassium ions in patients with primary aldosteronism in contrast to those with cushing's syndrome. Other forms of secondary hypertension (renal artery stenosis, pheochromocytoma, and accelerated essential hypertension) are being evaluated on similar protocols, as controls for those patients who have adrenal cortical causes of hypertension.